Marine 'superfertilizer' is crucial for life in the ocean and on land, including humans

Half the oxygen in your next breath did not come from trees on land. Scientists estimate that phytoplankton in the ocean make about half of the oxygen in the air in Earth’s atmosphere.

These microscopic drifters depend on nutrients that large whales move to the sunlit surface when they release nutrient rich waste.

Field research shows that marine mammals enhance primary productivity by concentrating nitrogen near the surface through flocculent fecal plumes.

Phytoplankton and oxygen

After decades of field work, Robert Kenney, an emeritus marine research scientist at the University of Rhode Island (URI), has traced how whales, prey, and currents shape each season. His perspective helps connect nutrients, food webs, and survival across years.

Phytoplankton are tiny photosynthetic organisms that turn sunlight and carbon dioxide into sugar and oxygen. Zooplankton are small animals that graze on them and feed fish, seabirds, and whales.

When nutrients are scarce near the surface, phytoplankton growth slows and the whole food web tightens. When nutrients pulse upward, growth accelerates and energy ripples through the system.

Whales often feed at depth and then return to the surface to rest, breathe, and digest. When they defecate near the surface, their waste carries nitrogen and iron that phytoplankton can use right away.

That burst of nutrients supports fast growth, which boosts food for krill and fish in the upper ocean. Many large whales filter this prey using baleen, flexible plates in their mouths that act like a sieve.

The loop continues when predators eat that prey and release nutrients again in shallow water. Over time, this recycling keeps productivity higher than it would be without whales.

Oxygen, carbon, and phytoplankton

More phytoplankton means more oxygen released at the sea surface. It also means more carbon pulled from the air and stored in living tissue and sinking particles.

Large whales add a second benefit when they store carbon in their bodies for decades, and when they die, their bodies sink.

Economists and ecologists have estimated that each great whale sequesters about 33 tons of carbon dioxide on average over its life.

These connections link whale recovery to climate and air quality in a practical way. They also link the health of fisheries to nutrient cycling in surface waters.

Industrial fleets in the 1900s used steam power and explosive harpoons to catch whales across every ocean. Researchers tally nearly 2.9 million large whales taken during the twentieth century.

Those losses did not just remove bodies. They weakened the nutrient recycling that living whales perform near the surface.

Even after hunting bans arrived, many populations recovered slowly. Maturity takes years, calves are few, and human pressures did not stop at the dock.

Right whales at the edge

North Atlantic right whales remain listed as endangered under the Endangered Species Act, with about 370 individuals left based on the latest federal assessment.

Their biggest risks today come from entanglement in fishing gear and vessel strikes in busy shipping lanes.

“The North Atlantic right whale is one to really worry about right now,” said Kenney. Population growth has lagged for years, and births have not offset human caused losses.

These whales feed mainly on dense patches of tiny crustaceans. When those prey shift with temperature and currents, right whales range farther and face greater hazards.

Reducing preventable deaths is the fastest way to help this species. Every adult female that survives increases future calves and stabilizes the population.

Blue whales and fin whales

Blue whales are the largest animals to have ever lived, and they feed mainly on krill using baleen plates to filter dense swarms. They can weigh well over 100 tons and may eat several tons of prey in a single day during peak feeding.

Fin whales, the second largest species, have begun to rebound in some waters after hunting stopped. Their recovery remains uneven because ship traffic and changing prey conditions still pose risks.

Both species contribute to nutrient recycling when they feed and defecate near the surface. Their presence signals a productive system that supports everything from forage fish to top predators.

Climate change and food webs

Ocean warming and acidification can shuffle where prey species live and how abundant they are across seasons.

For right whales, shifts in the distribution of cold water copepods can force longer searches in riskier places.

Whales can dive below the thermocline, a layer where temperature changes quickly with depth, to find cooler water.

They still need dense patches of prey near the surface to build the energy reserves needed for migration and calving.

As conditions change, managers may need dynamic protections that move with prey and whales. Tools that adjust routes and speeds in real time can reduce risk when animals appear.

Keeping nutrient cycles strong also means limiting excess pollution that can trigger harmful algal blooms. Clean water supports balanced growth rather than chaotic swings.

Phytoplankton, oxygens, and humanity

Slow speed zones for ships, ropeless fishing gear, and targeted closures during peak whale presence can reduce preventable deaths.

Coastal economies that depend on tourism and fisheries benefit when whale populations are healthy.

Reducing pollution and greenhouse gases limits additional stress on the systems that support oxygen production and seafood.

Protecting whales returns nutrients to the surface ocean, supports fisheries, and boosts natural carbon storage.

Household choices matter less than rules that shape fleets and shipping lanes, but both count. Each avoided collision or entanglement helps rebuild populations that lift productivity across the sea.

The ocean gives back when we protect the animals that keep its cycles moving. That includes air to breathe, food to eat, and a climate we can live with.

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